completely stumped. high idle

[southrneclipser]

95 eclipse 420a

i didn't have idle problems until i changed my head gasket. i got it all put back toether and cranked it up and now bounces around at idle from 1200 rmp to 2000 rpm. I changed the TPS and IAC. My vac lines are eliminated except to the brake booster. I changed the Throttle body gasket too.

When i let off of the gas, the rpm's very slowly fall. It feels more like a vacum leak but i can't figure out from where.

I took the TB off to clean it and when i spray the throttle plate with degreaser, it leaks to the other side. Also when its running and i put my hand over the intake, it brings the idle down, but if i put my finger over the little hole in front of the throttle plate (where the IAC sucks in air) it does nothing. So it seems like air is leaking into through the throttle plate even when its completely closed. Has this happened to anyone? Should i get a new throttle body?

i was planning on getting a jeep TB but i understand there are a few mods you have to do to make it work. Does anyone know what to do?

 

[#40Fan]

Check the intake manifold gaskets. There are two of them. Upper and lower. If you didn't have the intake apart I doubt the upper could be bad. Get some carb cleaner and spray around where the intake meets the head. When the idle changes, you found the leak.

 

[Kickerbeast]

I would check the throttle body very closely and make sure that nothing is holding the plate open at all. Try taking the cable off and see if the idle settles down. Also, you'll want to log your O2 when you try spraying for leaks. Many times the computer will see the extra fuel you are adding from spraying carb clean and it will lean out the mixture to compensate. You could spray the leak and not even know it. Watch your O2 and see if it goes full rich and holds there for a sec. You can also check the Evap system. I'm not sure on the 2G but there should be some way that the Evap system recirculates fuel tank vapors into the intake. Find that hose and clamp it off with some vice grips and see if that works. I have seen other makes have a high idle because they were sucking air past the recirculation solenoid.

 

[southrneclipser]

i didn't remove the intake mani from the head but i'll do that tomorrow. Also im not sure what you mean by the evap system. The only thing that i know off that recirculates is the egr.
Also there is absolutely nothing holding the throttle plate open

 

[FaNtUm2113]

did you check the throttle cable to make sure its not to tight? i know thats simple but sometimes the simple stuff is the things that get missed

 

[cjridert1]

+1 on the throttle cable, see if you can get the car to idle any lower by manually closing the diaphragm a bit further.

 

[southrneclipser]

even with the throttle cable off and the BISS completely out and i'll push the throttle plate completely closed with my hand it still idles high. I'm going to soak the TB in some degreaser in a little bit to see if that will break some of the gunk loose.

 

[Kickerbeast]

Wait...BISS completely out? Should be the other way. Unless they changed something on the 2G, and I'm pretty sure they are the same. In (screwed in) should lower the idle and out (screwed out) should raise it. If you have the screw completely out, that would be the same as pulling a vac line off. Also if you did take it out, did you check your o-ring. I took mine out and it was hard as a rock. I got another ring from the hardward store and it is golden now.

 

[southrneclipser]

sorry i meant the biss completely closed. but ill look into getting a new seal

ok so its not the BISS.

I bought some carb cleaner and sprayed the upper and lower intake mani's and nothing changed. Then a sprayed into the TB and it brought the idle down. I put my finger over the hole where the IAC sucks in air and sprayed some more in it and it pulled the idle down again. So air is leaking in the TB some freaking how. Its not any vac lines or seals or gaskets. Its leaking past the throttle plate. I guess i'll go get a new TB. Thanks everyone for the help.